All the diagnostic muscle biopsy cases were collected from the file of Department of Pathology, Seoul National University Hospital during June 1976 to December 1978. Slides were reviewed and correlated with clinical informations. Two hundred seventy four cases showed pathological changes, which were classified into six large groups (Table 1). Neurogenic atrophy was most common, 97 cases (35%), including 71 cases of motor neuron disease and 22 cases of peripheral neuropathy. Muscular dystrophy was seen in 92 cases (34%), and Duchenne type was the commonest among them (51 cases). Fifty seven cases showed inflammatory myopathy, making 20% of all cases. There were four cases of congenital myopathy and 13 cases showed various muscle diseases.